Soil moisture preference in the antlion Baliga micans (Neuroptera: Myrmeleontidae)

Abstract

Pit-building antlion larvae require not only dry and loose sand, but also other abiotic factors for beneficial pit site selection. Although wet soil is generally avoided by antlions, we assumed that antlion larvae of Baliga micans (McLachlan) (Neuroptera: Myrmeleontidae) prefer some degree of soil moisture because their relatively higher respiratory rate may cause water loss. We conducted behavioral experiments for pit construction in soils of different moisture content (0–29%) to quantitatively clarify soil moisture preference. Under the control containing only dry soil, some larvae died, no pits were frequently found, and larval weight decreased. The larvae constructed pits on the wet soil more frequently than on the dry soil. Particularly, the 2nd- and 3rd-instar larvae preferred the 9% soil and the 17% soil moisture, respectively. Therefore, the larvae showed soil moisture preference, owing to a probable physiological constraint. The soil moisture preference that secures the survival period is possibly a requisite trait for effective foraging.